Assumed Knowledge (Geometry and graphs) 5
SPECIAL QUADRILATERALS
There are six special quadrilaterals:
The following properties of quadrilaterals are useful:
PARALLELOGRAM
In any parallelogram: ² opposite sides are equal in length
² opposite angles are equal in size
² diagonals bisect each other.
RHOMBUS
In any rhombus: ² opposite sides are parallel
² opposite angles are equal in size
² diagonals bisect each other at right angles
² diagonals bisect the angles at each vertex.
RECTANGLE
In any rectangle: ² opposite sides are equal in length
² diagonals are equal in length
² diagonals bisect each other.
KITE
In any kite: ² two pairs of adjacent sides are equal
² the diagonals are perpendicular
² one diagonal splits the kite into two
isosceles triangles.
SQUARE
In any square: ² opposite sides are parallel
² all sides are equal in length
² all angles are right angles
² diagonals bisect each other at right angles
² diagonals bisect the angles at each vertex.
parallelogram rectangle rhombus square trapezium kite
² Aparallelogramis a quadrilateral which has opposite sides parallel.
² Arectangleis a parallelogram with four equal angles of 90 o.
² Arhombusis a quadrilateral in which all sides are equal.
² Asquareis a rhombus with four equal angles of 90 o.
² Atrapeziumis a quadrilateral which has exactly one pair of parallel sides.
² Akiteis a quadrilateral which has two pairs of equal adjacent sides.
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Y:\HAESE\IGCSE01\IG01_at\005IGCSE01_AT.CDR Tuesday, 18 November 2008 12:06:59 PM PETER
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